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Allowance for emergency opening of locks (Impression technique (indentation))

Пособие по аварийному открыванию замков (Импрессионная техника (вдавливания))

Technique indentation - possession of this method of hacking can talk about the hacker's professionalism. Long and painstaking work associated with the gradual grinding of a file with extra areas of metal key, part of which is responsible for secrets, this happens until the key becomes a copy of the native.

The undoubted advantages include the fact that you have a fully working duplicate, with which you can easily open the lock next time. Master keys do not give such effect.

This text is a translation of the English version of the manual published online. (translation author Alexey Goncharenko,


The knowledge and application of the indentation method is invaluable for emergency door opening services. In contrast to the disassembly / cracking method, this push-in method provides not only the opening of the lock, but also the manufacture of the corresponding key. This means that the indentation method (key selection) is not only effective, but also very economical. These working materials on indentation technology are divided into three main groups:

  • Locks with disc restraints (levers)
  • Locks with pin holders
  • Locks with cylinder and cross bolt

All this forms the basis of a theory on a technology called IMPRESSION TECHNOLOGY (Indentation Technique).

Table of contents

  • Introduction
  • Basics of indentation technique
  • Markings / prints
  • Preparation of key blanks
  • Rotation and pressure
  • Types of keys
  • Locks with cylinder - cross bolt
  • Concluding remarks

1 Basics of indentation technique

The theoretical side of technology.

First, the key blank is prepared for operation.


  • Surface file processing
  • File file processing
  • File Edging

  • And - processing by a file of one edging (angle 45 °)
  • B - double-edged file processing (with opposite angles of 45 °)
  • C - Blackening / coloring

Each of these methods is described in detail in the chapter on making blanks for a key.

Fingerprinting procedure.

1. The key for the key, made for the pressing-in method, is inserted into the channel of the lock cylinder. You must ensure that the disc is inserted into the cylinder as far as possible. In this case, you should not make too much effort.

2. Firmly hold the key with special tongs. Then it should be very firmly clamp the head of the key inserted into the cylinder with tongs. To do this, it is best to use special tongs. These forceps have soft sponges, so scratches cannot form on the pig. It should be monitored then that the tongs of the tongs are parallel to each other, since only in this case the greatest effort is provided to hold the key blank.

3. Now turn the key inserted into the cylinder to the right until it stops. At the same time, it is necessary to pay attention to the fact that too much force is not applied, since it is possible to break or bend the blank.

4. In conclusion, the block clamped with tongs should be pressed several times up or down. Because only thanks to such movements there are visible imprints on the blank.

5. During the subsequent working cycle, turn the key inserted into the cylinder to the left until it stops. At the same time, you should also pay attention to the fact that too much force is not applied, since it is possible to break or bend the disc.

6. Now you can remove the disc from the cylinder.

Your blank must, during all work processes, that is, from preparing the blank to the subsequent manufacture of the key, remain clamped in the tongs. Only in this way it is possible to provide a feeling of constancy of unity in the combination “blanks and tongs” and to avoid mistakes due to uneven clamping of the blanks.

The result of the manipulations will lead to the fact that the cylinder pins left obvious traces of markings or imprints on the blank.

Now the question is, why prints appear?

When inserting the blank, the cylinder pins are squeezed to a different height. If the pig is turned all the way, then it should be assumed that no cylinder is manufactured without manufacturing tolerances or cannot be manufactured. One of these tolerances is the drilling tolerance; that is, the drillings for the pins with their centers are not strictly on one line, but are slightly offset from the centerline. From this it follows that the pins are blocked at different times. As a result, markings or prints appear, either while rotating to the right or left as far as they will go.

When turning the blanks in the cylinder until it stops, the internal pins, which are located in the zone of the separation gap, are blocked in their position.

The contact between the pins of the core and the housing is created when the blank moves up and down. Markings and prints occur when moving up and down, and not due to the rotation of the blanks, as is often assumed.

In places where markings and fingerprints are visible, file processing is further performed.

The above-mentioned processes for obtaining markings and prints are repeated until the cutouts formed at the appropriate places during the file processing reach the corresponding depth at which the core pins can be moved out of the separation gap. In this case, the force of contact between the pins of the case and the core will not be sufficient to leave clear markings or imprints on the key.

The main rule of impression technique is: No file processing in areas where you can not see clear markings or prints!

When performing file processing, you should always remove only a little material, that is, jumps not more than 0.5 mm. Naturally, in this case, the production of the key is a little slower, however, working carefully, you can avoid having to start work all over again if too much material is suddenly removed.

Markings / prints

Markings and prints on the key blank arise because the key blank made of metal is pressed against the holding devices in the cylinder (pins / discs), which are also made of metal.

Every time when metals come into contact with each other or rub and scratch their surfaces, there is a marking or imprint.

For the impression technique, this means that these markings or prints must be clearly recognizable in order to process the file in the right place. At the beginning of the impression process, markings are difficult to determine, but at the end of the process they become larger, easier to identify and process.

Attention: If, at the beginning of the impression process, too much marking is obtained at a certain section or at a completely specific depth, in most cases this indicates that the following factor occurs:

  1. In this section, it is actually about depth No. 1. In this case, the impression process for this pin in the cylinder is completed.
  2. When preparing the key blank, too much material was removed. This is a big defect for the impression technique, since even before the work begins, the conditions for its termination are created.

Thus, an improperly prepared blank will each time be labeled at the appropriate place while there is nothing to grind on it. This phenomenon is explained by the fact that the housing pin is already in the zone of the separation gap. If the movement is left or right, it is not the core pin that is blocked, but the body pin. Therefore, with each subsequent workflow, new markings or prints are made.

It is important to understand that the markings created by the impression technology can be very different from each other.

These differences depend on the following two factors:

  1. on the type of lock used with the cylinder, i.e. pin or disc restraints (levers), etc.
  2. from the point at which markings are created during the workflow, i.e. at the beginning, in the middle or at the end.

The type of marking is determined by the design of the holding devices of the lock to be opened. In principle, two different forms of marking are distinguished:

  • line markings produced by lock discs with disc restraints (levers).
  • dot marking produced by lock pins with pin holding devices.
Allowance for emergency opening locks

The closer you approach the end result of the closures (cuts), the more distinct the markings become.

Allowance for emergency opening locks

The size and depth of individual markings vary from the very beginning to the end of the impression process.

The closer you approach the corresponding depth of the corresponding closures (cuts), the more distinct the markings become, as long as they should be considered as final or final markings.

After processing the blank with a file, the covering surface should be mirror-smooth. Only in this case will it be possible to distinguish initially weak markings.

File file processing

When processing with a file, the covering surface of the blank is prepared only in those places where, according to the measurement, there must be short circuits on the cylinder. These areas should also be mirror smooth.

File file processing after measuring distances

Preparation of key blanks

There are four effective methods for preparing blanks:

  • Surface file processing
  • File file processing
  • File Edging
  • Blackening or staining of contact planes

Surface file processing

With this method, the file is easily processed by the locking plane of the blank, so that there is neither chrome nor paint on it, so that after the first impression process (fingerprinting) it is possible to clearly distinguish the markings that have appeared and determine the distance between the individual closures.

Then further impression processes are carried out, as already described earlier.

Attention: When processing a blank with a file, remove less material than is required for the closure itself.

If you remove too much material, the consequence may be that the markings will not be accurate and the workflow will become impossible.

File Edging

For filing edgings there are two ways below:

  • Two-sided file processing of the locking surface of the blank at an angle of 45% each time, and you get a edge that looks like a knife blade. This means that from the flat surface of the blanks, it is necessary to remove evenly under the corners of the chamfer.
  • One-sided file processing of the locking surface of the blank at an angle of 45%. This means chamfering from the side face of the blank.

During both preparation options, care should be taken not to remove too much material from the file.

In case of locking cylinders with pins in the body, it is also important that the edge of the billet pass under the center of the axis of the cylinder pins. Many services working with keys readily use these two options, as the sharp edge allows to accurately determine the distance between short circuits and, moreover, markings in more difficult cases with locks with retaining devices (levers) and a crossbar.

You should try both options and choose a working option that provides you with the best result.

Blackening and staining of the contact surface of the blank

When blacking or coloring the contact surface of the blank, this is a method in which the markings become visible in the opposite way. This means that after blackening or dyeing, the blanks do not receive a dark marking on a light background, but instead a light marking on a dark background.

In this case, there are also several training options.

1. Blackening with soot

With this workflow, the corresponding blank is kept above the lit lighter and directly above the flame. At the same time the pig is covered with soot and becomes black. The marking is due to the fact that the disks or cylinder pins remove the soot layer, and in these places you can then see the pure metal of the blank, which is the marked point.

2. Painting

Here, too, the corresponding blank at the first operating cycle is covered with the coloring fluid. As a rule, it is a paint from a felt-tip pen with a felt rod or a marking varnish when processing metal products. Marking occurs as described when soot is used.

3. Ultraviolet kit

As with blackening with soot and dyeing, the blank at the first operating cycle is coated with a coloring fluid, but in this case we are talking about a fluorescent liquid.

After taking the markings or prints, keep the blank under the UV lamp. This special light provides clear visibility of markings and prints, since the corresponding places become visible much darker than the other locking area, which glows under an ultraviolet lamp.

The methods described above are of course not the only methods for preprocessing and preparing key blanks. They are only the most common and effective methods, and everyone can decide for himself what he would prefer. It is best if the user tries each method in different conditions and under different light conditions.


Step 1

The key blank is prepared for work using the impression technique technique, namely:

  • Surface file processing
  • File file processing
  • File Edging
  • Blackening / staining

Step 2

The key blank is inserted possibly deeper into the cylinder shut-off channel.

Step 3

Turn the key blank with a moderate effort to the right. Press up and down

Step 4

Key blank several times strongly push up and down. Then, with moderate pressure, turn the blank all the way to the left. After that, the blank several more times strongly push up and down.

Step 5

Remove the key blank from the cylinder, and check the markings. At the location of the markings, the material is removed by a file, but only where the markings are. Places without markings should not be processed, even if the distances between the closures are fixed.

The above stages of work 1 - 5 should be repeated as long as the locking key is not received.

Training, practical application and experience make a specialist out of the user by this method. Practice is especially important in order to be able to distinguish the necessary markings from insignificant ones.

For most users, it is the application of this technology that is on the verge of their visual abilities.

However, poor eyesight is not an obstacle, since it can be compensated for by modern grinding of magnifying glasses or working loops, which, depending on the version, can be illuminated or unlit.

It should again be recalled that the rotational movement all the way must be performed with moderate effort, if only because with great effort it is impossible to obtain recognizable markings. There is only the danger that the key blank will be broken or bent.

Special care is required if there are disc restraints and cylinders with a cross bolt. With these systems, with too much force, the cylinder may be damaged during rotation, as the washers or pins will be bent.

On the other hand, a little effort is not enough to block the pins. As a result, markings either do not appear at all or do not appear very vague prints.

In order to successfully use the impression technology, the user must be trained for a long time in obtaining the correct rotational force.

Here are the books that allow you to get even more valuable knowledge in the castles. Lock letters.

SA McLean, "The Impression System of Key Fitting", Dire Locksmith
Supply Co., 2201 Broadway, Denver, Colorado 808205, 1946 "Locksmithing and Keymaking Course Manual", Locksmithing Institute, Little Falls, New Jersey, 1968
"Padlock Handbook", Locksmith Ledger, 2720 Des Plaines Ave., DesPlaines, Ill., 60018, 1970
"How To Do It For Locksmiths", Locksmith Ledger, 1800 Oakton St., DesPlaines, Ill., 60018, 1971
"Know How for Locksmiths", Locksmith Ledger, 1970
"The Lock Pick Design Manual", Paladin Press, PO Box 1307, Boulder, Colorado 80302, circa 1975
TC Mickley, "Lock Servicing, Volume 4", Locksmith Ledger, 850 Busse Highway, Park Ridge, IL 60068, 1980
Eddie the Wire, "How to Make Your Own Professional Lock Tools, Volume 2", Loompanics Unlimited, PO Box 1197, Port Townsend, WA 98368, 1981
Hank Spicer, "Impressioning with Hankman", RSG Publishing Corp., Dallas, Texas, 1995

The remaining parts of the publish does not make sense, since it is already intended for professionals.

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